Localization needles or wire guides are utilized for preoperative marking of nonpalpable breast lesions. Typically, a needle cannula having a wire guide contained therein is inserted into the female breast and preferably positioned within two centimeters of the lesion. A mammogram or other visualization aid is used to confirm the position of the distal needle end. If the needle is not accurately positioned with respect to the lesion, the needle is repositioned, and another mammogram is taken to visualize the repositioning of the needle end with respect to the lesion. When the needle position is acceptable, the wire guide is extended from the distal end to localize the breast lesion for recision by the surgeon. Alternatively, the wire guide is maintained in a fixed position while the needle is removed to expose the wire guide contained therein. Similarly, the distal end of the wire guide localizes the breast lesion for recision by the surgeon. A number of prior art wire guides are utilized for localizing breast lesions. One in particular is the Kopans breast lesion localization needle that includes a spring-hook wire guide that is manufactured by Cook, Inc. of Bloomington, Ind. After the spring-hook wire guide is extended from the localization needle adjacent the breast lesion, the spring-hook wire guide remains relatively fixedly positioned. The guide may be further extended into the breast tissue either intentionally or unintentionally; however, the spring-hook prevents inadvertent removal of the wire guide from the breast tissue. This advantageously prevents retraction or removal of the wire guide due to inadvertent movement of the breast during transportation or movement of the patient. However, it does not prevent inadvertent advancement into the breast. Repositioning of the spring-hook wire guide is limited, and removal is by surgical resection.
A number of repositionable localization systems are also presently available. The HAWKINS.TM. breast lesion localization system manufactured by Boston Scientific Corporation of Watertown, Mass., includes a rigid cannula with a retractable side barb for repositioning the needle cannula if necessary. Some physicians prefer the rigid cannula; however, others do not. The rigid cannula also presents the risk of further penetration through the breast and into the chest cavity and lungs as a result of patient movement.
Another repositionable localization system is the Homer MAMMALOCK.TM. needle/wire localizer, which is available from Namic.RTM. of Glens Falls, N.Y. The MAMMALOCK localizer includes a needle with a unique alloy J-hook wire positioned within the needle, which is extendable therefrom. The needle is introduced into the breast tissue, and the J-hook wire advanced into the tissue before a mammogram is taken for accuracy of placement. The J-hook wire tip protects the breast tissue from needle point penetration during breast compression. However, the J-hook tip includes a straight segment at the distal end which presents a significant disadvantage should the needle be removed. The curved portion of the J-hook wire tip does not track the straight segment at the distal end of the wire when extended from the distal end of the needle. As a result, the J-hook wire tip does not penetrate the tissue and is deflected from the lesion should the needle be subsequently removed. The deflection and lack of tractability significantly increase the difficulty of accurate placement of the wire guide. Trial-and-error placement of the guide also subjects the patient to unnecessary radiation received during the taking of extra mammograms.
Another repositionable wire guide having a memory hook for localizing breast lesions is disclosed in U.S. Pat. No. 4,616,656. This wire guide includes a relatively small hook with a pointed distal end. The wire guide is preferably made of a memory characteristic material which assumes the J-hook configuration in response to body heat. The J-hook may be repositioned after retraction into a sheath and re-extension into a new position. When the wire guide is acceptably positioned, the cannula is removed, and the wire guide is left as a guide for surgical excision of the lesion. This repositionable wire guide is also subject to the same disadvantages as those of the MAMMALOCK J-hook wire guide. Furthermore, the J-hook wire guide does not fixedly position or lock in breast tissue and is easily dislodged during transportation or movement of the patient. In addition, the J-hook wire tip design is hard for the surgeon to palpate.